With developments in the mobile communication field, various mobile communication systems have emerged, for example, a Global System for Mobile Communication (GSM), an Enhanced Data for GSM Evolution (EDGE) system, a GSM/EDGE Radio Access Network (GERAN) system, a Wideband Code Division Multiple Access (WCDMA) system, a Code Division Multiple Access (CDMA) system, a Code Division Multiple Access 2000 (CDMA2000) system, a Time Division-Synchronous CDMA (TD-SCDMA) system, a Long Term Evolution (LTE) system under development and establishment, a World Interoperability for Microwave Access (WIMAX) system, etc. The WCDMA system may also be referred to as Universal Mobile Telecommunications System (UMTS). Due to the emergence of the various systems, when a terminal performs cell reselection during movement, there may be several frequencies available for selection in the system, and there may be many cells of several systems available for selection. Therefore, it becomes an important issue as to how the terminal reselects a suitable cell and how to reduce measurements to save power energy.
In the current LTE system, considering that the terminal should reduce measurement overhead to save power energy, when performing cell reselection, the terminal will decide a cell on which the terminal is to camp according to the priority. Specifically, the terminal will first measure a frequency or system having a higher priority. If a cell of the frequency or system having a higher priority meets the cell reselection criterion, the cell will be reselected; otherwise, a cell having a lower priority will be measured. If a terminal camps on a cell having a lower priority, a cell having a higher priority might be measured periodically. The priority-based cell reselection method may reduce the measurements by the terminal and save power energy. Meanwhile, a good priority setting may lead to load balance.
In the existing technical solutions, the terminal performs cell reselection by using a dedicated priority list established by the non-LTE mobile communication system. The Access Network (AN) node or the Core Network (CN) node has to add more signaling for establishment of the dedicated priorities, which leads to higher costs for network upgrade.